1. Field of the Invention
The present invention generally relates to a method of treating surfaces of semiconductor substrates, and more particularly, to an improved method in which surfaces of a plurality of semiconductor substrates can be treated at one time.
2. Description of the Background Art
FIG. 10 is a conceptual diagram of a conventional etching apparatus. The etching apparatus shown in the figure is used for cleaning semiconductor substrates or for etching away oxide films formed on surfaces of semiconductor substrates. In a conventional etching apparatus, semiconductor substrates are treated one by one.
Referring to FIG. 10, the etching apparatus includes a cylindrical reaction chamber 1. The reaction chamber 1 and a gas bomb 4 in which hydrofluoric acid gas or the like is accommodated are connected to each other by a Teflon pipe 5. Teflon pipe 5 includes a mass flow controller 6 and valve 8 for controlling the flow rate of the hydrofluoric acid gas or the like.
A pipe 7 is connected to Teflon pipe 5 for flowing a nitrogen gas into the Teflon pipe 5. A mass flow controller 10 and a valve 9 for controlling the flow rate of the nitrogen gas are provided in pipe 7.
Reaction chamber 1 and a vacuum pump 11 are connected by a pipe 12. The vacuum pump 11 is used for removing gas or air inside reaction chamber 1. A valve 13 is provided in pipe 12.
A susceptor 3 for supporting a semiconductor substrate 2 such as a silicon substrate is provided in reaction chamber 1. A lid 14 for hermetically closing the reaction chamber 1 is provided over reaction chamber 1.
Next, operation of cleaning semiconductor substrates will be described.
The lid 14 is opened and semiconductor substrate 2 is provided on susceptor 3. The lid 14 is closed. Valves 8 and 9 are closed and a pump 11 is operated with valve 13 being open to exhaust air inside reaction chamber 1. Next, valve 9 is opened for replacement by a nitrogen gas inside reaction chamber 1. Subsequently, valve 8 is opened to introduce a hydrofluoric acid gas or the like into reaction chamber 1. With the hydrofluoric acid gas or the like introduced into reaction chamber 1, cleaning of semiconductor substrate 2 or etching of an oxide film on the surface of semiconductor substrate 2 is performed. Valve 8 is closed for replacement by a nitrogen gas inside reaction chamber 1 again. Subsequently, valve 13 is closed to recover the atmospheric pressure with nitrogen gas inside reaction chamber 1. Lid 14 is opened to take out semiconductor substrate 2. At this time, a semiconductor substrate to be treated next is provided on susceptor 3. After closing lid 14, the above-described process is repeated again.
As described above, semiconductor substrates are treated one by one in a conventional etching apparatus. Accordingly, every time a piece of semiconductor substrate is introduced into reaction chamber 1, air inside reaction chamber 1 had to be exhausted to replace it with nitrogen gas inside reaction chamber 1. Accordingly, it takes a long time to treat a single piece of semiconductor substrate, resulting in a problem that the capability (through put) of treating semiconductor substrates is low.